A miniaturized glucose biosensor in which glucose oxidase (GOD) and poly(p-phenylenediamine) (poly-PPD) were coimmobilized at the surface of a platinum microdisk electrode was developed and used successfully for amperometric determination of glucose. The performance of sensors prepared at different monomer concentrations and polymerization potentials with different media was investigated in detail. It was found that similarly to poly(o-phenylenediamine) (poly-OPD), (poly-PPD) noticeably eliminated the electrochemical interference of ascorbic acid, uric acid, and l-cysteine. The amperometric response of glucose with the biosensor under optimal conditions exhibited a linear relationship in the range of 5.0 x 10(-5) to 3.0 x 10(-3) M with correlation coefficient 0.9995. According to the Michaelis-Menten equation, the apparent Michaelis constant for glucose and the maximum steady-state current density of the poly-PPD/GOD-modified microelectrode were 3.94 mM and 607.5 microA cm(-2), respectively. The current density of the sensor responding to glucose in the linear range can reach 160 microA cm(-2) mM(-1), which is far greater than that obtained using poly-OPD and poly(phenol) film. In addition, the stability of the sensor was examined over a 2-month period.